So first off, we have to either get Application added to the spec or change it
to X-Application (and update our .menu files). Also we have to make
desktop-file-install not choke on categories that start with X-

I believe "Application" would be a bit redundant, since all the desktop files
that are relevant for menus should have Type=Application anyway.
Another thing that the validator may want to check is the main/additional category
distinction made in the menu spec.

It barfed on me too, with "Application" (which I'm going to remove if that's
intentionally not valid), "X-Fedora" and "X-Red-Hat-Base". Does it already know
(again) about the "X-" category exception? I'd like to be able to build again ;-).